i2c.c

I2C总线的驱动程序

/*************************  IC Card AC Characteristics  *******************************************
Symbol		Parameter					2.7-volt		5.0-volt		Units
									Min		Max		Min		Max		
fSCL		Clock Frequency,SCL		   		100		    	400			kHz
tLOW		Clock Pulse Width Low	4.7		   		1.2		   			μs
tHIGH		Clock Pulse Width High	4.0		   		0.6		   			μs
tI			Noise Suppression Time	   		100		   		50			ns
tAA			Clock Low to DICATa Out 	0.1		4.5		0.1		0.9			μs
			Valid
tBUF		Time the bus must be	4.7		   		1.2		    		μs
			free before a new
			transmission can start
tHD.STA		Start Hold Time			4.0				0.6					μs
tSU.STA		Start Setup Time		4.7				0.6					μs
tHD.DICAT		DICATa In Hold Time		0				0					μs
tSU.DICAT		DICATa In Setup Time		200				100					ns
tR			Inputs Rise Time				1.0				0.3			μs
tF			Inputs Fall Time 				300				300			ns
tSU.STO		Stop Setup Time			4.7				0.6					μs
tDH			DICATa Out Hold Time		100				50					ns
tWR			Write Cycle Time				10				10			ms
Endurance	5.0V,25℃,Page Mode		100K			100K				Write Cycles

***************************************************************************************************/


unsigned int IC_Output(unsigned char b)
{
unsigned char	i;

	IC_CLK = 0;
	i = 8;
	while(i--)
	{
		IC_IO = (b & 0x80) >> 7;
		b = b << 1;
		delay(5);
		IC_CLK = 1;
		delay(5);	//tHIGH
		IC_CLK = 0;
	}
//check ACK
	IC_IO = 1;
	delay(5);
	IC_CLK = 1;
	if ((IC_IO & 1) == 1) {
		IC_CLK = 0;
		return(0);
	}
	delay(5);
	IC_CLK = 0;
	return(1);
}

unsigned char IC_Input(unsigned char ack)
{
unsigned char	b,i;

	IC_CLK = 0;
	IC_IO = 1;	//release the bus
	i = 8;
	b = 0;
	while(i--)
	{
		b = b << 1;
		IC_CLK = 0;
		delay(5);	//tLOW
		IC_CLK = 1;
		delay(2);	//none
		if (IC_IO & 1) b = b | 1;
		delay(5);	//tHIGH
	}
	IC_CLK = 0;
	IC_IO = ack;		//give ACK or nonACK
	delay(5);
	IC_CLK = 1;
	delay(5);
	IC_CLK = 0;
	return(b);
}

void IC_Start(void)
{
	IC_CLK = 0;	
	IC_IO = 1;
	delay(5);	//tLOW
	IC_CLK = 1;
	delay(5);	//tHD.STA
	IC_IO = 0;
	delay(5);	//tSU.STA
	IC_CLK = 0;
}

void IC_Stop(void)
{
	IC_CLK = 0;	
	IC_IO = 0;
	delay(5);	//tLOW
	IC_CLK = 1;
	delay(5);	//tHD.STO
	IC_IO = 1;
	delay(5);	//tSU.STO
}

unsigned char IC_Read(unsigned short int addr,unsigned short int len,unsigned char *ptr)
{
unsigned short int	i;

	if (!IC_PROBE ) return(1);
	if (len == 0) return(5);
	IC_ENABLE;	//上电
	i = 0;
	delay(100);	//等待
//	EA = 0;

IC_Rstart:
	IC_Start();
	//Set current address
	if ( !IC_Output(0xa0) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	if ( !IC_Output( 0x1f & HIBYTE(addr+i) ) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	if ( !IC_Output( LOBYTE(addr+i) ) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	//Sequential Read
	IC_Start();
	if ( !IC_Output(0xa1) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	while(1)
	{
		if( (len == i + 1) || ( ((addr+i+1)&0x1f) == 0 ))
		{
			ptr[i] = IC_Input(1);
			i++;
			break;
		}
		else ptr[i] = IC_Input(0);
		i++;
	}
	IC_Stop();
	/*EA = 1;*/
	if (len != i)
	{
		/*EA = 0;*/
		goto IC_Rstart;
	}
	/*EA = 1;*/
	IC_DISABLE;
	return(0);
}

unsigned char IC_Write(unsigned short int addr,unsigned short int len,unsigned char *ptr)
{
unsigned short int	i;
unsigned char	t;

	if (!IC_PROBE) return(1);
	if (len == 0) return(5);
	IC_ENABLE;	//上电
	i = 0;
	delay(100);	//等待
	/*EA = 0;*/

IC_Wstart:
	IC_Start();
	//Set current address
	if ( !IC_Output(0xa0) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	if ( !IC_Output( 0x1f & HIBYTE(addr+i) ) ) {/*EA = 1;*/IC_DISABLE;return(2);}
	if ( !IC_Output( LOBYTE(addr+i) ) ) {/*EA = 1;*/IC_DISABLE;return(2);}
//	t = 0;
	do
	{
		if ( ! IC_Output(ptr[i]) ) {/*EA = 1;*/IC_DISABLE;return(2);}
		i++;
	}
	while((len != i) && ( ((addr+i)&0x1f)!=0 )  );

	IC_Stop();
//Stopped
	/*EA = 1;*/
	for (t = 0; t < 30;t++)
	{
		delay(550);//505us
	}
//Wait for internal write cycle about 10ms
	if (len != i) 
	{
		/*EA = 0;*/
		goto IC_Wstart;
	}

	/*EA = 1;*/
	IC_DISABLE;
	return(0);
}

void ICP(unsigned char	i)
{
	switch (i)
	{
		case 0:
			//Dprintf("操作成功!");
			break;
		case 1:
			//Dprintf("未检测到IC卡!");
			break;
		case 5:
			//Dprintf("函数调用错误！");
			break;
		case 2:
			//Dprintf("I/O错误，跳回");
			break;
		default:return;break;
	}
	return;
}